A mid-span winch is held between an anchor point and an object to be pulled toward the anchor point. A mid-span winch is usually held to the anchor point by a fixed-length strap, rope or cable and it has its retractable strap, rope or cable attached to the object to be moved. Of course, an opposite mounting can also work. The fixed-length strap, rope or cable is referred to hereinafter as the fixed-length towline, for convenience. Similarly, the retractable strap, rope or cable is referred to herein as the retractable towline.
In a manual mid-span winch, a hand crank operates the winch reel to wind the retractable towline and to pull the object toward the anchor point.
Unlike a common winch that is affixed to a solid structure, a manual mid-span winch is often suspended above ground to its fixed-length towline and retractable towline. A movement of the crank handle causes the mid-span winch to wobble back and forth from the axis of the towline, and to twist back and forth about the axis of the towline. An increase in tension in the towline reduces to some degrees the up and down movements of the winch. The side to side movements of the winch and the twisting of the winch about the pulling axis, however, remain substantially undiminished as tension increases. These wobbling and twisting movements cause significant difficulties in the operation of the crank handle and in the winding of the towline on the reel of the winch.
When a rope is used on the winch reel, the wobbling and twisting movements of the winch makes it difficult to wind the rope evenly, one layer at the time on the reel. In these cases, the rope tends to stack up at the ends of the reel.
When a strap is used as a towline, the wobbling and twisting motions of the winch body cause the strap to rub against the mouth of the winch and to fold over itself before it is wound on the reel. It will be appreciated by those using winches that both a rubbing of the strap edges against the mouth of the winch; the folding of the strap over itself, and the stacking up of a rope at the ends of a reel are undesirable defects in the operation of a winch, and can lead to precarious operation of the winch.
In order to appreciate the challenges associated with manual mid-span winches, two examples of manual mid-span winches of the prior art are listed herein below. These prior art manual mid-span winches belong to the same class as the manual mid-span winch described hereinafter.
U.S. Pat. No. 1,177,767 issued to R. N. Eggleston on Apr. 4, 1916. In this document, a crank-operated winch is described. The winch is used to pulled a car out of a mud-hole. The winch is suspended by chains between the car bumper and a series of conveniently-installed anchor spikes. The problems associated with the wobbling and twisting of the winch body in use have not been addressed in this publication. However, one can appreciate that the setup described therein is not easy to operate.
U.S. Pat. No. 1,806,606 issued to G. M. Booth on May 26, 1931. This document also discloses a mid-span winch with a hand-operated crank. An extensible leg prop has been provided under the winch body to secure the winch body to the ground when working the crank. The leg prop stabilizes the winch body against unwanted wobbling and twisting movements.
Although the leg prop in the last-mentioned document deserves some merits, there is still a need in the field of manual mid-span winches for a better way to counteract the wobbling and twisting actions of a winch body in use.